I was driving my Honda ST 1100 to Toronto from central Alberta a few years ago and, as is my custom, I stopped at the side of the road to stretch my legs in North Dakota along Highway 52.

As I looked around, I noticed numbers inscribed on the nearby hills. The numbers were in pairs—i.e. 66, 89, 91, 90. For some strange reason, I got it right away. I knew that these numbers were created by graduating classes from a local high school.

When I later looked it up, it turns out I was right.

The inscriptions have been left by graduating classes of Kenmare High School. In a tradition that stretches back to 1945, graduating classes have organized Rock Day. High school seniors select a hill and get to work. They use shovels to dig out sod, fill the indent with rocks and apply whitewash or paint to ensure that their graduating year is visible for all to see.

Many of the graduating years apply fresh whitewash during reunions, helping to ensure that their year is preserved in posterity.

All but a few graduating classes have taken up the rock challenge.

It was a lovely place to stop and stretch, and another example of the interesting sights you see when you take the road less ridden.